1. Field of the Invention
The present invention relates to a socket for an electric part and more particularly, to a socket for an electric part for providing an electric connection between terminals of the electric part and an external electric test circuit in order to carry out a performance test of the electric part.
2. Description of the Related Art
In order to carry out the performance test of an electric part such as a semiconductor device or the like, a socket for an electric part for providing an electric connection of terminals of the electric part with an external electric test circuit is conventionally used in many cases.
In such a socket for an electric part, a positioning plate is disposed on a socket body, so that the electric part is placed on the positioning plate. Contact pins are disposed on the socket body, and a slide plate slidable in a horizontal direction is disposed between the positioning plate and the socket body. Further, an operating member for moving the slide plate is disposed for vertical movement relative to the socket body.
In this socket, the slide plate is slid in the horizontal direction through a link mechanism by lowering the operating member, thereby resiliently deforming one of resilient pieces of a contact pin to open upper ends of the resilient pieces. Thereafter, an electric part is placed on the positioning plate, and the operating member is lifted, thereby moving the slide plate back to its original position to release an urging force on the contact pin. This permits the contact pin to be returned to its initial position under its resilient force, whereby the tip ends of the contact pins clamp terminals of the electric part and as a result, the electric connection of the electric part is achieved.
However, such conventional socket for the electric part suffers the following problem: Since the slide plate is slid in the horizontal direction through the link mechanism by lowering the operating member, it is necessary to convert a downward urging force to a force in the horizontal direction perpendicular to an urging direction and hence, a larger force for urging. the operating member is required.
Another problem is as follows: One of the resilient pieces of the contact pin is opened out, whereby each of the terminals of the electric part is clamped by the resilient pieces and hence, a larger amount of movement of the resilient piece is required. For this reason, the repulsion force of the contact pin is increased, and hence, a larger force is required to move the slide plate. A further problem is that the load stress on the contact pin is increased to bring about a reduction in life of the contact pin.
Accordingly, it is an object of the present invention to provide a socket for an electric part, wherein the slide plate can be moved easily by urging the operating member by a smaller force.
To achieve the above object, according to a first aspect and feature of the present invention, there is provided a socket for an electric part, comprising a socket body having a plurality of contact pins disposed thereon, each of the contact pins having resilient pieces capable of clamping each of terminals of an electric part, a slide plate disposed above the socket body and movable in a substantially horizontal direction, and an operating member disposed movably in a vertical direction relative to the socket body for sliding the slide plate, so that the slide plate is moved by the vertical movement of the operating member, whereby tip ends of the contact pins are opened and closed to come into and out of contact with the terminals of the electric part, wherein a plurality of the slide plates movable in opposite directions are laminated vertically on one another, each of the slide plates being provided with contact pin-pressing portions for opening the contact pin; the socket body having operating arms turnably disposed thereon and connected to the slide plates for moving the slide plates; and the operating member has operating projections disposed thereon for turning the operating arms by vertical movement of the operating member, so that the operating arms are turned by the operating projections by urging the operating member downwards, thereby moving the slide plates.
With the arrangement of the first feature, the operating projections of the operating member turn the operating arms by urging the operating member downwards, thereby moving the slide plates in the opposite directions. With this movement of the slide plates, the contact pin-pressing portions provided on the slide plates open the resilient pieces of each of the contact pins into their states in which each of the terminals can be clamped by the resilient pieces. Therefore, the amount of movement of each of the resilient pieces of the contact pin can be reduced by half, and the repulsion force of each of the resilient pieces is also reduced. As a result, the slide plates can be moved by a smaller force.
According to a second aspect and feature of the present invention, in addition to the first feature, each of the slide plates has plate arm portions provided thereon, and each of the operating arms has an operating pin formed at its intermediate portion, so that the operating arms and the slide plates are interconnected by bringing the operating pins into engagement with tip ends of the plate arm portions.
With the above arrangement of the second feature, the operating pins formed at the intermediate portions of the operating arms are brought into engagement with the tip ends of the plate arm portions provided on the slide plates, thereby connecting the operating arms to the slide plates. The tip ends of the operating arms are urged by the operating projections provided on the operating member to move the operating pins on the operating arms bya principle of lever, thereby move the plate arm portions to move the slide plates. Therefore, the slide plates can be moved easily, and the operating member can be urged by a smaller force.
According to a third aspect and feature of the present invention, in addition to the first or second feature, the operating arms are connected at their base ends to each other, so that they are turned about connected portions thereof.
With the above arrangement of the third feature, the operating arms are connected at their base ends to each other, so that they are turned about the connected portions. Therefore, a repulsion force produced upon movement of the slide plates can be countervailed by the connected portions of the operating arms.
According to a fourth aspect and feature of the present invention, in addition to any of the first to third features, the turnable portions of the operating arms are disposed in the vicinity of a center of movement of each of the slide plates.
With the above arrangement of the fourth feature, the turnable portions of the operating arms are disposed in the vicinity of a center of movement of each of the slide plates and hence, when the operating member is urged, the urging of the operating member can be carried out stably.
The above and other objects, features and advantages of the invention will become apparent from the following description of the preferred embodiment taken in conjunction with the accompanying drawings.